Scrubbing apparatus for polluted gases

ABSTRACT

A liquid screen scrubbing apparatus for effectively and efficiently removing insoluble and soluble solid, liquid and gaseous pollutants and materials valuable for by-product recovery from gases such as products of combustion and other atmospheres of industrial processes. The apparatus is located in a flue between one or more sources of polluted gases and a point of discharge, the apparatus including longitudinally spaced rows of vertically disposed elongated tanks, the rows extending transversely of the flue. The tanks in a row are angularly oriented and spaced from each other, and the tanks in adjacent rows are staggered. Each tank is crescent-shaped in horizontal cross section, and the concave wall thereof faces generally upstream toward the gas source. Liquid such as water continuously flows down the concave upstream walls of the tanks forming liquid screens, and when gases moving through the flue impinge on the flowing liquid, the insoluble and soluble pollutants such as dust, liquid droplets, SO2, SO3, Co, etc. and by product materials are entrained or dissolved in, and carried away by, the liquid. The tanks may be mounted for rotation on vertical axes, and thus subject to variation of the angular orientation in the manner of an adjustable damper between substantially closed position and desired open positions. The gases have tortuous travel paths through the apparatus, and the paths and pressure drop in the apparatus are determined by the angular orientation of the tanks. There are optimum angular settings for the crescent-shaped tanks to provide the most efficient removal of the solid and soluble pollutants and by-product materials of given gases under given conditions of gas velocity.

United States Patent 91 Rowley 1 SCRUBBING APPARATUS FOR POLLUTED GASES[75] Inventor: Harold A. Rowley, Palos Heights, 111. [73] Assignee: M.H. Detrick Company, Chicago,

Ill.

[22] Filed: June 3, 1970 [21] Appl. No.: 43,042

52 US. Cl. ..ss/241, 261/17, 261/112,

261/DIG. 19 [51] Int. Cl. ..Bld 47/12 [58] Field of Search ..55/240,241; 261/3,

261/112, 17, DIG. l9

[5 6] References Cited UNITED STATES PATENTS 3,353,800 11/1967 Jens..26l/3 1,989,774 2/1935 ...26l/l 12 3,475,012 /1969 Britton et a]...261/1 12 3,313,533 4/1967 Powers ...26l/ll2X 3,458,178 7/1969 Wamick..261/l7 3,440,803 4/1969 Wechselblatt ..26l/l 12 X 3,018,847 1/1962Stanlk ...261/1 12 X 2,133,819 10/1938 I-Iowse et a1. ..55/24l X FOREIGNPATENTS OR APPLICATIONS 450,439 7/1936 Great Britain ..55/241 PrimaryExaminer--Robert L. Lindsay, Jr.

Attorney-Prangley, Dithmar, Vogel, Sandler & Stotland 1 Apr. 10, 1973ABSTRACT A liquid screen scrubbing apparatus for effectively andefiiciently removing insoluble and soluble solid, liquid and gaseouspollutants and materials valuable for by-product recovery from gasessuch as products of combustion and other atmospheres of industrialprocesses. The apparatus is located in a flue between one or moresources of polluted gases and a point of discharge, the apparatusincluding longitudinally spaced rows of vertically disposed elongatedtanks, the rows extending transversely of the flue. The tanks in a roware angularly oriented and spaced from each other, and the tanks inadjacent rows are staggered. Each tank is crescent-shaped in horizontalcross section, and the concave wall thereof faces generally upstreamtoward the gas source. Liquid such as water continuously flows down theconcave upstream walls of the tanks forming liquid screens, and whengases moving through the flue impinge on the flowing liquid, theinsoluble and soluble pollutants such as dust, liquid droplets, S0 S0C0, etc. and by product materials are entrained or dissolved in, andcarried away by, the liquid. The tanks may be mounted for rotation onvertical axes, and thus subject to variation of the angular orientationin the manner of an adjustable damper between substantially closedposition and desired open positions. The gases have tortuous travelpaths through the apparatus, and the paths and pressure drop in theapparatus are determined by the angular orientation of the tanks. Thereare optimum angiillar settin s for the crescent-shaped tanks to grovidee most e lclent removal of the solid and solu le pollutants andby-product materials of given gases under given conditions of gasvelocity.

1 Claim, 11 Drawing Figures PATENTED 1 W a; 726 064 SHEET 1 [1F 3PATENTEBAPH 1 0191s 3, 725 ,05

snmams SCRUBBING APPARATUS FOR POLLUTED GASES CROSS REFERENCE TO RELATEDPATENT Reference is made to U.S. Pat. No. 3,353,800, dated Nov. 21,1967, issued to -Wilmer C. Jens, assignor to the assignee of the presentinvention.

BACKGROUND OF THE INVENTION This invention relates to liquid screen gasscrubbers, and more particularly to scrubbing apparatus used withindustrial furnaces, refuse incinerators, materials processing apparatusand the like (grinders, buffers, ball mills, screeners, rotary dryingkilns, etc.) for the purpose of eliminating or minimizing the dischargeof gases containing insoluble and soluble pollutants and by-productmaterials of value. In performing this function, the apparatus also mayvary in adjustable manner the flow of gases between the gas source and apoint of discharge. The flow adjustment is accomplished by rotatablymounting the scrubbing elements so they may provide damper action. Ofcourse, the scrubbing elements with fixed angular orientation also havea damping action on the gas flow.

As far as is known by applicant, the aforesaid Jens Pat. No. 3,353,800and the references cited during the prosecution thereof constitute theclosest prior art. No reference shows crescent-shaped tanks with wettedconcave wall surfaces for a liquid screen, or discloses a liquid screenwhich also constitutes a damper.

SUMMARY OF THE INVENTION The apparatus of the invention includes screensof downwardly flowing liquid such as water in a flue between one or moregas sources and a point of discharge. Substantially all the gases in thesystem impinge against or are exposed to liquid of the liquid screens asthey travel along guided tortuous paths across the screens toward thepoint of discharge. Insoluble and soluble pollutants and by-productmaterials in the gases are entrained or dissolved in, and carried awayby, the liquid, and the remaining gases which are discharged (usuallyto'atmosphere) are comparatively free of objectionable pollutants andare at desirable temperature.

The liquid screens are formed by a plurality of vertically disposedelongated tanks which are crescentshaped in horizontal cross section.The tanks are arranged in longitudinally spaced rows extendingtransversely of the flue. The tanks in each row, except when closed, arespaced from each other, and the tanks in adjacent rows are staggered,thereby cooperating to provide tortuous paths for the gases. The concavewalls of the crescent-shaped tanks face generally upstream toward thegas source.

The liquid constituting the aforesaid screens flows down the concavewalls of the tanks, and is collected at the bottom and carried away forprocessing or discharge. The angularly oriented concave and convex wallsof the tanks produce comparatively smooth guided flow of the gases inthe system. In preferred form, the exterior surfaces of the concavewalls have a roughened texture or longitudinal ribs, or both, whichcooperate to enhance the quantity of pollutants removed from the gases.

The liquid screens on the concave tank walls provide highly efficientscrubbing action. A substantial portion of the gases and pollutants ofthe gases impinge on the wetted concave walls of the first row of tanks,and a quantity of pollutant enters the liquid and is removed. Theconcave walls of the tanks in the first row direct the gases smoothlythrough the spaces between tanks into directed engagement with thewetted concave walls of the tanks in the second row. Additionalpollutants are then removed, and the gases are directed to the third rowof tanks, etc. The concave and convex walls engaged by the gasesminimize the tendency toward turbulence, and thus minimize the drop indraft pressure caused by the scrubbed system. Further, the curved wallsprovide increased wall and liquid screen area in the same linear space,compared with flat walls, thereby enhancing scrubbing efficiency.

The tanks in the transverse rows preferably are mounted for rotation onvertical axes, and are subject to rotation between closed position andpredetermined open positions, thereby providing damping action andcontrolling the draft pressure drop and the amount of air or oxygenflowing into the gas source. The source is a combustion chamber when thegases are products of combustion.

The damping action of the present apparatus permits optimum utilizationof the available draft pressure, regardless of whether the draftpressure is large or small, natural or induced. Also, in an installationhaving an induced draft blower with ducts providing a by-pass to astack, the rotatable tanks may be closed to establish the by-pass incase of blower failure, or failure of the liquid supply to the tanks.

The apparatus of the invention is used to advantage in connection with aplurality of gas sources, such as furnaces, served by the same media ofdraft pressure. When a furnace or other gas source is shut down formaintenance or other reason, some or all of the rotatable tanksassociated therewith may be closed to isolate that gas source from thedraft media.

The drawings and following description thereof relate specifically tofurnaces, but it is to be understood that the invention also isapplicable to other gas sources such as above mentioned, and the claimsare to be read accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic planvieW,.Partly in section, of a two-furnace installation utilizing thescrubbing and damping apparatus of the invention.

FIG. 2 is a diagrammatic elevational view, partly in section, showingthe furnace installation of FIG. 1.

FIG. 3 is a top plan view, partly broken away, of a scrubbing anddamping apparatus embodying the invention.

FIG. 4 is a fragmentary sectional view on line 4-4 of FIG. 3.

FIG. 5 is a fragmentary sectional view on line 5-5 of FIG. 4.

FIG. 6 is a fragmentary perspective view of one form of crescent shapedtank for use in the invention.

FIG. 7 is an exploded elevational view, partly in section, of anotherform of crescent shaped tank for use in the invention, the tank beingformed of a plurality of sections.

FIG. 8 is a sectional view on line 8--8 of FIG. 7.

FIG. 9 is a bottom view of the tank shown in FIG. 7.

FIG. 10 is a fragmentary sectional view on line I10- 10 of FIG. 7.

FIG. 11 is a fragmentary sectional view on line 11- 11 of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate oneform of furnace installation utilizing the scrubbing and dampingapparatus of the invention, the installation including two furnaces eachhaving separate scrubbing and damping apparatus, a single fan providinginduced draft, a single stack for natural draft and discharge, andassociated flue and duct members.

FIG. 2 also effectively illustrates the use of the scrubbing and dampingapparatus of the invention in a one-fumace installation.

Referring to FIGS. 1 and 2, a furnace 15 or other source of pollutedgases has a flue 16 leading to scrubbing and damping apparatus 17embodying the invention, the latter having an outlet flue 18 leadingthrough induced draft fan 19 and outlet flue 20 to discharge stack 21. Aby-pass duct 22 with conventional damper 23 leads from flue 16 aroundscrubbing and damping apparatus 17 to connection with outlet flue 20 atjunction 24 (FIG. 2). The tanks in the downstream row of apparatus 17are shown in closed position, thereby establishing gas flow throughby-pass duct 22 and damper 23.

A second furnace 25 or other source of polluted gases has a flue 26which leads to scrubbing and damping apparatus 27, the latterdischarging into previously mentioned outlet flue 18. The products ofcombustion from furnace 25 remaining after passage through apparatus 27are directed through fan 19 and outlet flue 20 to stack 21. A by-passduct 28 with conventional damper 29 leads from flue 26 around apparatus27 and connects with the aforesaid outlet flue 20 at junction 24.

A dividing wall 30 separates the two flues l6 and 26 on the upstreamside of scrubber and damper apparatus 17 and 27.

The scrubbing and damping apparatus 17 and 27, as will be seen, performtwo main functions. First, they effectively and efi'rciently removeinsoluble and soluble contaminants and by-product materials from theproducts of combustion or other polluted gases, thereby minimizingpollutants discharged to at mosphere, and, second, they function asdampers (either fixed or movable) to achieve desired pressure dropconsistent with the available draft pressure. If movable, one or both issubject to closure in the event of failure of induced draft fan 19, or afailure of the liquid supply to the apparatus, or a need to isolate oneor both of the furnaces or gas sources for shutdown or repair.

Referring to FIGS. 3-5, scrubbing and damping apparatus embodying theinvention is generally designated 35. The apparatus, as mentioned, islocated in flue 16, 18 between a furnace or other gas source and aninduced draft fan. If no fan is used in the installation, apparatusdischarges into flue 18 which leads directly to an associated stack orother discharge arrangement.

Scrubbing and damping apparatus 35 includes an upper support generallydesignated 36 (FIGS. 4 and 5) and a lower support 37, the upper andlower supports 36 and 37 cooperating to mount vertically a plurality ofelongated tanks 40 which are crescent-shaped in horizontal crosssection.

As best shown in FIGS. 1 and 3, crescent-shaped tanks 40 are arranged ina plurality of rows 41, 42, etc. extending transversely of flue 16, 18,the tanks in each row being normally spaced from each other with theconcave walls 45 thereof facing generally upstream toward the combustionchamber or other gas source. The rows are spaced from each otherlongitudinally of the flue with the tanks in one row staggered withrespect to the tanks in an adjacent row.

As will be seen later, each tank 40 receives a continuous flow ofliquid, usually water, which fills the tank and overflows on theupstream concave wall 45. The liquid flows down the exterior surface ofeach wall 45, providing liquid screens in the path of the polluted gasesflowing through the apparatus. The gases and entrained particulates, ifany, impinge against one or more of the liquid screens and give up tothe flowing liquid insoluble and soluble pollutants such as dust, S0 S0CO, etc. The pollutant laden liquid is collected in the region of lowersupport 37 where it is discharged from a trough 47 (FIG. 4) or the liketo waste or to tanks for treatment and reuse.

Liquid is supplied to tanks 40 from a manifold or header 50 having a Tcoupling 51 (FIGS. 3 and 5) for each row of tanks. A pipe 52 leads fromT coupling 51 through a line valve 53 to a pipe 54 which feeds into adistribution pipe 55 best shown in FIG. 5. Separate fixed pipes 56 (FIG.5) lead from distribution pipe 55 to the respective tanks 40 in atransverse row.

Each tank 40 has secured thereto a pipe 60 which extends substantiallythe length of the tank, the pipe 60 terminating short of the tank bottomas shown at 61 in FIGS. 4 and 5. Pipe 60 extends upwardly above the topof tank 40 and is coupled to an aforesaid fixed pipe 56 by means of acoupling 63, a swivel coupling if the tank is to be rotatable. In theform of the invention shown, a fixed pipe 56 and associated coupling 63constitute the upper support for a tank 40.

As shown in FIGS. 4 and 5, the lower end of,each tank 40 has aprojecting member 65 received in a socket 66 or the like in lowersupport 37. Member 65 thus is rotatable on support 37 if desired.

Coupling 63 if a swivel coupling and projecting member 65 position atank 40 and permit variation in the angular orientation of the tank.With this arrangement, some or all of the tanks 40 in the apparatus maybe rotated to establish optimum paths for the products of combustion orother gases and to vary the drop of draft pressure. The latter, ofcourse, influences the velocity of the gases through the apparatus.

While rotatable tanks 40 may be adjusted individually, it usually isdesirable to gang together some or all of them. As shown by way ofexample in FIGS. 3-5, the several tanks in each transverse row 41, 42etc. are ganged together. Each tank pipe 60 in a row has secured theretoa link 67 (FIGS. 3 and 4), the several links 67 having uniformorientation with respect to pipes 60 and associated tanks 40. The freeends of links 67 in each row are pivotally connected to an actuatingmember 70, the member 70 at an accessible end having a cross bar 71(FIGS. 4 and 5) or other means for connection to a power mechanism (notshown) which for example operates pneumatically or hydraulically.

As will be understood from FIG. 3, back and forth movement of actuatingmember 70 causes rotation of tanks 40 to provide more or lessrestriction of the flow of products of combustion through the apparatusand to vary somewhat the length of the travel path for the pollutedgases.

In preferred form, the tanks 40 in each of the transverse tank rows 41,42 etc. are rotatable, and provided with an actuating member 70. Withthis arrangement, all tanks 40 are adjustable readily, and they usuallyare adjusted uniformly in angular orientation to establish tortuouspaths through the apparatus providing a desired drop in draft pressure,or to substantially close the apparatus to the passage of gases.

Referring to FIG. 6, the tank 40 there shown is formed from twopreformed metal plates 72 and 73 which differ in curvature and thusprovide a tank of crescent-shape in horizontal cross section. The twoplates are secured along their abutting edges 75 and 76 as by welding.Tank 40 is closed at its bottom with a bottom plate having the aforesaidprojecting member 65 which rotates on bottom support 37.

Convex downstream wall 77 of tank 40 extends upwardly beyond the topedge 78 of concave upstream wall 45, causing the liquid in the tank tooverflow and run down wall 45 only. A deflector plate 79 mounted atopconvex downstream wall 77 is a safety feature which protects workersfrom steam blasts when liquid is introduced into dry hot tanks duringrepair operations.

It has been found that the scrubbing action is enhanced by giving theexterior surface of concave wall 45 a roughened texture. Accordingly, inpreferred form, the wall 45 is roughened to a texture comparable tocoarse sandpaper as shown diagrammatically at 80 in FIG. 6. This textureserves to confine the liquid flowing down the wall 45 and resist thetendency of the liquid from being blown completely from the wall by theimpinging gases.

A modified form of crescent-shaped tank for use in the invention isshown in FIGS. 7-11. Here, the tank is made with a plurality of shortsections, each of suitable material such as cast iron or ceramicmaterial. As shown in FIGS. 7, 9 and 11, lower section 85 has adownwardly projecting boss 86 which supports the tank and permitsrotation. Intermediate tank sections 87 are of like size and shape,except for the boss, and both sections 85 and 87 have an upper margin 88of reduced dimension to telescope into the cooperating sectionimmediately above. Upper section 90 is cut away at the -top of concavewall 91 as shown at 92 to provide desired overflow from the tank on theconcave wall only. A deflector plate 93 is mounted at the top of uppersection 90 as a safety feature to protect workers.

A sectionalized tank of FIG. 7 preferably is provided with spacedlongitudinal ribs 95 (FIGS. 7-10) on the exterior surface of concavewall 91, and the surface of the wall given a roughened texturediagrammatically indicated by 96. Ribs 95 confine the flowing liquid andhelp prevent the liquid from completely being blown off laterally by thegases.

Referring further to FIG. 10, lower section has webs 98 between concavewall 91 and convex wall 99, and the same is true of the sections 87 and90. Webs 98 define circular openings 100, a liquid supply pipe 101 (FIG.7) extending through the openings of the several sections. Pipe 101 issecured to one of the sections so the tank may be rotated thereby, as bya threaded relationship with webs 98 in lower section 85 (FIG. 11). Insuch case, liquid flows from pipe 101 into the tank through lateralports 102 in the webs.

Referring back to FIGS. 3-5, upper support 36 for tanks 40 is enclosedby a sheet metal housing 103 disposed above the tops of tanks 40, asbest shown in FIGS. 4 and 5. A cover 104 hinged at 105 (FIG. 5) servesto minimize infiltration of outside air into the high-draft regionwithin the housing.

Removable horizontal baffle plates 106 (FIGS. 3-5) enclose the bottom ofhousing 103 to prevent furnace gases from entering the housing and thusby-passing tanks 40 and escaping the scrubbing action. In addition,transverse vertical baffles 107 (FIGS. 4 and 5) ex tend downwardly fromthe bottom of housing 103 between the rows of tanks 40, the lower edgesof baffles 107 being somewhat below the tops of the tanks. Verticalbaffles 107, which serve to support horizontal baffles 106, deflectfurnace gases away from the upper ends of tanks 40, thereby preventinggas passage through the space between the tank tops and horizontalbaffles 106. Also, as shown in FIGS. 3 and 5, lateral walls 110 and 111of flue 16, 18 have spaced vertical baffles 112 at one end of each tankrow to prevent the gases from flowing along the walls and thusby-passing the tanks.

As best shown in apparatus 17 in FIG. 1, downstream tank row, thespacing between tanks 40 in a transverse row of tanks is such that thereis a slight overlap of adjacent tanks when the tanks are rotated toclosed position whereby gas flow is blocked. When rotated away fromclosed position, space is provided between adjacent tanks for gaspassage. 7

An open position for the tanks 40 is shown in FIG. 3. This position, aswell as other open positions, establishes guided tortuous paths throughthe apparatus for the polluted gases. The tanks 40 in upstream tank row41 have uniform angular orientation, that is, the concave walls thereofall face in the same direction. The tanks 40 in adjacent row 42 likewisehave uniform angular orientation, but this orientation is not the sameas that in row 41. The tank orientation in row 42 is more or less thereverse of that in row 41 in terms of establishing path direction. Theuniform orientation in the next downstream row is like that in row 41,and the reverse of that in row 42.

With the tank inclinations and. orientations shown, the polluted gasesfollow smoothly guided zig-zag paths through the apparatus andexperience minimum turbulence. The concave upstream walls of the tanksin row 41 direct the gases through the spaces between the tanks in thatrow and into engagement with the reversely oriented concave walls of thetanks in adjacent row 42 where the direction of gas flow issubstantially reversed from the direction established by the tanks inrow 41. Successive reversals occur at each row in the system, causingthe gases to traverse a distance considerably greater than thelongitudinal distance through the apparatus. The gases and pollutantsimpinge on numerous liquid screens in this extended travel distance, andgive up substantial quantities of pollutants, and other materials whichmay have value in by-product recovery.

Particulate material such as dust is trapped by the liquid screen, andgases such as toxic gases or gases for by-product recovery, e.g., S S0CO, etc., are absorbed by the liquid screen. The liquid of the screen,as mentioned, is discharged to waste, or treated for neutralization,cleaning, or by-product recovery, and reused.

The liquid used in the apparatus in many instances can be reused withoutextensive cleaning, or indeed any cleaning, for the reason that theliquid at all times is under low pressure and there are no spraynozzles, valves or the like subject to malfunction due to small solidsin the liquid.

From the above description it is thought that the construction andadvantages of this invention will be readily apparent to those skilledin the art. Various changes in detail may be made without departing fromthe spirit or losing the advantages of the invention.

Having thus described the invention, what is claimed as new and desiredto secure by Letters Patent is:

1. In a flue between a source of polluted gases, such as a furnacecombustion chamber, refuse incinerator, or industrial processingapparatus, and a point of discharge, scrubbing and damping apparatus,comprismg:

upper and lower supports in effective relation with a plurality ofvertically disposed elongated tanks extending within said flue betweensaid upper and lower supports, each tank crescent-shaped in horizontalcross section, said tanks arranged in a plurality of rows extendingtransversely of said flue. the tanks in each row spaced from each otherwith the concave walls thereof facing generally upstream toward the gassource, the tanks having angular orientations providing gas travel pathsbetween adjacent tanks with entrance spaces wider than exit spaces, saidrows spaced from each other longitudinally of the flue with the tanks inone row staggered and reversely oriented angularly with respect to thetanks in an adjacent row, whereby gases flowing through the apparatusare guided smoothly by the concave tank walls on tortuous zig-zag paths;

means mounting said tanks on said supports including means mounting atleast some of said tanks rotatably on said supports and means forrotating said rotatable tanks between closed position where transverselyadjacent tanks are in engagement to block gas flow and predeterminedopen positions permitting gas flow through the apparatus, therebyproviding adjustable damping action and control of gas travel pathsthrough the apparatus; and

means providing a continuous flow of liquid down the concave upstreamwalls of said tanks, whereby insoluble and soluble particulates andcomponents of polluted gases impinging on said liquid are entrained anddissolved in and carried away by said liquid.

1. In a flue between a source of polluted gases, such as a furnacecombustion chamber, refuse incinerator, or industrial processingapparatus, and a point of discharge, scrubbing and damping apparatus,comprising: upper and lower supports in effective relation with saidflue; a plurality of vertically disposed elongated tanks extendingwithin said flue between said upper and lower supports, each tankcrescent-shaped in horizontal cross section, said tanks arranged in aplurality of rows extending transversely of said flue, the tanks in eachrow spaced from each other with the concave walls thereof facinggenerally upstream toward the gas source, the tanks having angularorientations providing gas travel paths between adjacent tanks withentrance spaces wider than exit spaces, said rows spaced from eaCh otherlongitudinally of the flue with the tanks in one row staggered andreversely oriented angularly with respect to the tanks in an adjacentrow, whereby gases flowing through the apparatus are guided smoothly bythe concave tank walls on tortuous zigzag paths; means mounting saidtanks on said supports including means mounting at least some of saidtanks rotatably on said supports and means for rotating said rotatabletanks between closed position where transversely adjacent tanks are inengagement to block gas flow and predetermined open positions permittinggas flow through the apparatus, thereby providing adjustable dampingaction and control of gas travel paths through the apparatus; and meansproviding a continuous flow of liquid down the concave upstream walls ofsaid tanks, whereby insoluble and soluble particulates and components ofpolluted gases impinging on said liquid are entrained and dissolved inand carried away by said liquid.